Wellhead completion apparatus



Sept 970 R. 0. BARNETT 3,526,418

WELLHEAD COMPLETION APPARATUS Filed July 25, 1968 Foerf .0. Bar/7e f fINVENIOR.

A77 PA/EV United States Patent 3,526,418 WELLHEAD COMPLETION APPARATUSRobert D. Barnett, Houston, Tex., assignor to Rockwell ManufacturingCompany, Houston, Tex., a corporation of Pennsylvania Filed July 25,1968, Ser. No. 747,708 Int. Cl. F161 35/00 U.S. Cl. 28593 4 ClaimsABSTRACT OF THE DISCLOSURE Wellhead completion apparatus comprising atubing head with a vertical bore therethrough, a tubing hanger disposedin said bore and a lockscrew assembly afiixed to the tubing head. Thebore of the tubing head is defined 'by an upper cylindrical portionjoined to a lower cylindrical portion by upwardly facing annularshoulder. The tubing hanger exterior is defined by an upper cylindricalportion and a lower cylindrical portion joined by a downwardly facingsurface in contact with the tubing bore shoulder to support the hanger.An annular groove is formed on the exterior of the hanger adjacent thelockscrew assembly. The lockscrew assembly includes a lockscrewlaterally movable through the tubing head wall to engage the annularhanger groove. Annular sealing rings are provided on the upper hangerportion above the groove and on the lower hanger portion below thegroove. These rings are in sealing contact with the tubing head borewalls.

BACKGROUND OF THE INVENTION Field of the invention This inventionpertains to apparatus for use in well completion operations. Morespecifically, it pertains to apparatus for hanging and holding tubingwithin a well.

Background of the invention It is common practice in the completion ofoil and gas wells to hang a production tubing string in a tubing headwhich is usually surmounted on a casing head. A tree assembly, normallyincluding a master valve and other valves and fittings, is then mountedon the tubing head.

It is also common to use lockscrews, passing through the upper tubinghead flange engaging the tubing hanger, to hold the tubing down. Unlessspecial pack-01f nipples and seals are used the lockscrews are exposedto full well pressure at all times. Should a leak occur in the lockscrewpacking, it would be necessary to kill the well for replacement, sincethe master valve is above the lockscrews. This, of course, is a veryexpensive procedure.

SUMMARY OF THE INVENTION The present invention provides a unique tubinghead, hanger and lockscrew arrangement whereby the lockscrews areisolated from high well pressures. The invention comprises a tubing headhaving a vertical bore therethrough and an upwardly facing shouldertherein; a tubular hanger supported on the shoulder and having annulargroove means on its exterior; lockscrew means on the tubing head, aportion of which is laterally movable through the walls of the tubinghead to engage the annular groove means, preventing longitudinalmovement of the hanger; and

3,526,418 Patented Sept. 1, 1970 annular sealing means on the hanger insealing contact with the tubing head isolating the lockscrew means frompressure above and below the hanger. Thus, the likelihood of a costlyleak is reduced. The arrangement also provides a simple testing methodwhereby the lockscrew packing and isolating seals may be easily testedat any time.

BRIEF DESCRIPTION OF THE DRAWINGS Further objects and advantages of theinvention will become apparent from the following description when takeninto conjunction with the accompanying drawing in which:

FIG. 1 is a schematic representation of a typical wellhead andproduction tree assembly, and

FIG. 2 is an elevation view, partially in section of a tubing head,tubing hanger, tubing and lockscrew arrangement according to a preferredembodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 1, atypical wellhead and production tree assembly is shown supported on asurface casing 2 penetrating the ground 3. A lowermost casing head 4 isattached to the surface casing 2 for supporting a casing hanger andanother casing (not shown) therein. Depending on the casing programcalled for another casing head 5 may be mounted above casing head 4 tosupport an intermediate casing hanger and casing (not shown).

Mounted on casing head 5 is tubing head 6 which supports therein tubinghangers and tubing through which the well production will flow. Casingvalve 7 gives flow access to the casing surrounding the productiontubing. Surmounted on tubing head 6 is an adapter flange 8, master valve9, tee 10 and tree top 11. A wing valve 12 is connected to one branch ofT 10 through which production fluids pass to a choke 13 and eventuallyto a flow line 14.

The tubing head 6 shown in FIG. 1 is one typical of presently usedequipment. It will be noticed that lockscrews 15 are provided in theupper flange. These lockscrews are used to engage tubing hangers (notshown) suspended within tubing head 6 to hold the hangers and theirattached tubing strings in the well against any upward force that may beexerted on them. Occasionally these lockscrews are damaged oninstallation or due to the high internal well pressures to which theyare subjected their packings begin to leak. Since they are below mastervalve 9, it is necessary to kill the well to replace or repair alockscrew or its packing.

With the tubing head, tubing hanger, and lockscrew arrangement of thepresent invention the lockscrews are isolated from high wll pressures.Thus, it is less likely that a leak will occur. Furthermore, theinvention provides a method of testing the lockscrew packing andisolating seals prior to bringing the well in. This gives assurance of agood seal before the Well begins to produce. A preferred embodiment ofthe invention is shown in FIG. 2 comprising tubing head 20, tubinghanger 30, tubing 40, and lockscrew assembly 50. The embodiment shown isfor a single tubing completion. The invention may also be adapted foruse with multiple completions, as can be understood.

Tubing head 20 is provided with a lower flange 21 for mounting on acasing head and an upper flange 22 on which a master valve and otherproduction tree components may be surmounted. The bore 23 of tubing headis provided with an upwardly facing shoulder 24 on which tubing hanger30 is supported. This support shoulder may be above or below lockscrewassembly 50. The bore of tubing head 20 immediately below shoulder 24 isof a smaller diameter than the bore thereabove for reasons to besubsequently understood.

Lockscrew assembly 50 comprises tubular housing 51, lockscrew 52,packing 53, inner packing gland 54, and outer packing gland 55. Tubularhousing 51 opens into tubing head bore 23 and is provided with threads56 for engagement of lockscrew threads 57 and threads 58 for engagementof outer gland threads 59. A nut member 60 is provided for rotatinggland 55 to adjust or replace packing 53. Lockscrew 52 is provided withflats 61 for engagement of a wrench or the like allowing lockscrew 52 tobe withdrawn from or projected into tubing head bore 23. The inner endof lockscrew 52 has a frusto-conical nose portion 62 which in theinwardly projecting position shown engages tubing hanger 30 preventingupward movement thereof.

Tubing hanger 30 is a tubular member with upper and lower innerconnection means such as threads 28 and 29. A tubing string 40 isattached to the lower connection. The upper connection may be connectedto a handling string for installation or removal of hanger 30 and itsattached tubing string 40. The exterior of hanger 30 comprises an uppercylindrical portion 31 and a lower cylindrical portion 32. The diameterof lower portion 32 is slightly less than upper portion 31 so that adownwardly facing surface 33 is provided to cooperate with tubing headshoulder 24 for supporting hanger 30 within the head 20. Near the bottomof upper cylindrical portion 31 and above support surface 33 an annulargroove 34 with bottom wall 35 and side walls 36 and 37 is cut tocooperate with the frusto-conical nose 62 of lockscrew 52 to hold hanger30 and tubing 40 against upward movement. Groove 34 could also be placedbelow support surface 33 if desired. Since the nose 62 of lockscrew 52is usually of a harder material than hanger 30, lockscrew 52 mayslightly deform hanger 30 near groove walls 36 and 37. This may scratchthe bore of tubing head 20 when the hanger is removed. To eliminate thisproblem annular relieved areas 47, 48 are provided above and belowgroove 34. This allows some deformation without bore interference.

Immediately above hold down groove 34 are two adjacent annular grooves38 in which are mounted annular sealing rings 39 and annular back-uprings 41. This upper sealing means isolates lockscrew assembly 50 fromthe high pressures existing in the upper part of tubing head 20.Immediately below support shoulder 33, on lower reduced diameter portion32, are two more adjacent annular grooves 42 in which are mountedannular sealing rings 43 and annular back-up rings 44. This lowersealing means isolates lockscrew assembly 50 from the pressures existingin the lower part of tubing head 20 and casing therebelow. This pressurecould become quite high if tubing string 40 should dev lop a leak, whichis quite common. Thus, lock screw assembly '50 is completely isolatedfrom high pressure environments by the upper and lower sealing means.Lockscrew packing 53 will be less likely to develop a leak and thelockscrew assembly 50 may be of a more economical design withoutsacrificing safety or performance.

A port 45 may be formed in the wall of tubing head 20 through whichpressure can be applied to test both lockscrew packing 53 and the upperand lower sealing assemblies of tubing hanger 30. This can be done priorto bringing in a well so that a complete seal can be assured onceproduction is b gu To install hanger 30 and tubing string 40 in a well ahandling string would be attached to the upper inner connection means 28of hanger 30 and the hanger 30 would be lowered into head 20, lockscrew52 being fully retracted from the bore thereof until downwardly facingshoulder 34 contacts tubing head support shoulder 24. Since the lowerportion 32 of hanger 30 is of a diameter smaller than the hanger upperportion 31, it is readily seen that the seal rings 43 of the lowersealing assembly are not in contact with the tubing head walls untilthey pass support shoulder 24. Thus, the likelihood of damaging the sealon installation is considerably reduced. Once the hanger 30 has beenseated on support shoulder 24, lockscrew 52. may be turned until nose 62fully engages the walls of hold down groove 34 restraining hanger 30 andits supported tubing string 40 against longitudinal displacement.Pressure may then be applied through port 45 to test the seals 39, 43and lockscrew packing 53. Assuming that the test is positive, the wellcan be brought in. The lockscrew, being isolated from high internal wellpressures, will not be likely to develop a leak which would require acostly shutdown.

Although only one preferred embodiment of the invention has beendescribed herein, many modifications thereof can obviously be made byone skilled in the art without departing from the spirit of theinvention.

What is claimed is:

1. Wellhead completion apparatus comprising:

a tubing head having a vertical bore therethrough, said bore defining anupper cylindrical portion and a smaller diameter lower cylindricalportion with an upwardly facing support shoulder therebetween;

a tubular hanger supported within said bore on said support shoulder,the exterior of said hanger comprising an upper cylindrical portion, asmaller diameter lower cylindrical portion and annular groove means;

lockscrew means attached to said tubing head, a portion of which islaterally movable through the walls of said tubing head engaging saidgroove means to prevent longitudinal movement of said hanger;

first annular sealing means on said hanger upper portion above saidgroove means in sealing contact with said tubing head upper portion;

second annular sealing means on said hanger lower portion below saidgroove means in sealing contact with said tubing head lower portion; and

at least one test port passing through the wall of said tubing head andcommunicating with said groove means to pressure test said first andsecond sealing means and said lockscrew means.

2. Wellhead completion apparatus as set forth in claim 1 characterizedby annular relieved areas above and below said annular groove meansimmediately adjacent thereto.

3. Wellhead completion apparatus as set forth in claim 1 characterizedin that said groove means is on one of said upper and lower cylindricalportions.

4. Wellhead completion apparatus comprising:

a tubing head having a vertical bore therethrough, said bore comprisingan upper cylindrical portion and a lower cylindrical portion with anupwardly facing annular support shoulder therebetween;

a one piece tubular hanger disposed in said bore having on its exterioran upper cylindrical portion, a lower cylindrical portion, annulargroove means and a downwardly facing support surface joining said upperand lower cylindrical portions and cooperating with said supportshoulder to support said hanger on said tubing head;

a tubing string directly connected to said tubular hanger and supportedthereby;

lockscrew means, attached to said tubing head, lateral- 1y movablethrough the walls thereof to engage said groove means preventinglongitudinal movement of said hanger and tubing string relative to saidtubing head;

first annular seal on said hanger above said groove means and secondannular seal on said hanger below said groove means in sealing contactwith said tubing head isolating said lockscrew means from thepressurized environment of said tubing head above said hanger and aroundsaid tubing string; and

a test port passing through the wall of said tubing head andcommunicating with said groove means to test said first and second seal.

References Cited UNITED STATES PATENTS Pinkard 285142 X Smith 285-404 XRoach et al 28593 X Parkhurst et al. 285-133 X Musolf 285133 X Rector285-93 X Knight 285-27 DAVE W. AROLA, Primary Examiner US. Cl. X.R.

